Prevalence of hyperthyrotropinemia in obese children before and after weight loss

Background Obesity is a worldwide epidemic. In recent years, increasing attention has been focused on thyroid function in obesity. Objectives To establish the prevalence of elevated thyroid-stimulating hormone (TSH) levels in obese children and adolescents, and identify the relationship between TSH levels and other metabolic and hormonal variables before and after weight reduction. Materials and methods We evaluated 150 obese subjects (aged 3-17 years) for anthropometric, biochemical, metabolic and hormonal variables. Measurements were taken at baseline and, in a subgroup of children with hyperthyrotropinemia, after a 6-month intervention program based on exercise, behavior therapy, and nutrition education. Results At baseline, 23 participants (15.3 %) had hyperthyrotropinemia, and 21 of these patients completed the weight reduction intervention. Among these 21 patients, 14 had substantial weight loss and a significant decrease in TSH and free T3 levels. Conclusion We conclude that TSH and T3 levels are significantly increased in childhood obesity; in most cases, however, these increases cannot be elucidated by thyroid autoimmunity or iodine deficiency. If thyroid disorders are excluded beforehand, an elevated TSH with normal thyroid hormone levels in obese children seems rather a consequence than a cause of obesity since weight loss leads to a normalization of elevated TSH levels. In this context, thyroid hormone alterations in obesity suggest an adaptation process.